DIN 10779:2011-03

This standard specifies a HPLC method for determination of 16-O-methyl cafestol content in roasted coffee. The method is tested for a mass fraction of 50 mg to 300 mg 16-O-methyl cafestol content per kg of roasted coffee. Precision of the method has been determined in an interlaboratory test with 8 participating laboratories. This standard has been prepared by the Food and Agricultural Products Standards Committee, Working Committee "Coffee" and has been published for the first time in 1999. Since the first edition has been published it became clear that the table given in Annex A containing validation data is misleading. Therefore, it was considered necessary to reformulate the annex. For the determination of the 16-O-methyl cafestol content in roasted coffee, the sample is first subjected to a fat extraction with tert-Butylmethylether (tBME). After finished extraction, the coffee lipids are saponified with ethanolic potassium hydroxide solution under reflux; then the unsaponifiable matter is separated by extraction with tBME. After distilling off the solvent, the residue is taken up in a defined amount of dichloromethane. An aliquot is dried, taken up with the defined amount of HPLC eluent and examined using high-performance liquid chromatography. Detection is carried out at a wavelength of 220 nm. Identification is carried out by comparison of the relevant retention time with the respective standard substance. Quantification is then carried out according to the method of the extern standard via the peak areas.